1. Field of the Invention
The present invention relates to apparatuses and methods for filling a drum with a fluid.
2. Description of the Related Art
There is often a need to fill containers with a compound such as a fluid or other substance. For example, systems are typically employed to fill containers with a fluid, such as a chemical or petrochemical type solution. Cylindrical containers called drums are typically used for this purpose. Drums may be of various capacities or sizes. For example, some drums hold a "barrel" (42 gallons) of liquid, or other quantities such as 55 gallons. So-called "tighthead drums" contain an opening for filling at the top, sometimes called a "bunghole." "Open head" drums, on the other hand, which do not have a bunghole, are also sometimes employed.
Drums are typically filled by moving them through a "booth," which contains filling equipment. There are typically three general stages involved in filling a drum: orientation, filling, and capping. Referring now to FIG. 1, there is shown a prior art drum filling system 100 which illustrates these stages. System 100 comprises orientation stage 110, filling stage 120, and capping stage 130, as well as linear conveyor 103 and filling booth 127. Booth 127 contains blower (or blowers) 135, lance 134, and inlet (ingress) and outlet (egress) doors 121, 122, respectively. A tighthead drum 101, having bunghole 102, is typically "indexed," or moved, through the three stages 110, 120, 130 on conveyor belt 103. In orientation station or stage 110, drum 101 is oriented, typically by a device called an "orientator." This device may be automated, and typically spins the drum until bunghole 102 is properly positioned for filling in the next stage, filling station or stage 120. (For open head drums, orientation stage 110 may be skipped, or it may be used to spin the drum for jet-coding or other purposes.)
Drum 101 is then indexed by conveyor 103 to filling stage 120, i.e. to the inside of booth 127. Inlet door 121 opens on the incoming side of filling both 127, to allow the now-oriented drum 101 to be indexed into the booth, so that lance 134 can be lowered into bunghole 102 to fill drum 101 with a given fluid. (Sometimes the orientator and thus orientation stage 110 is also positioned within booth 127, in which case booth door 121 is opened to allow drum 101 to be indexed into the booth to be oriented and filled.)
Booth 127 is employed at filling stage 120 so that a blower 135 (such as centrifugal blower) can capture vapor, fumes, or other gaseous emissions that escape during the filling process. Blower 135 can then appropriately process these emissions, depending upon their nature and the nature of the liquid which fills drum 101, for example by using vents, scrubbers, or an incinerator.
After filling in filling stage 120, drum 101 is indexed by conveyor 103 out of booth 127, to capping station or stage 130. Outlet door 122 on the outgoing side of booth 127 typically opens in conjunction with this indexing, to allow the drum out of the booth. At the capping stage 130, a manual (human) or automatic operator caps bunghole 102 so as to seal the drum. (For open head drums, the capping stage involves applying an entire top "lid" to the drum instead of simply capping a bunghole.)
One problem involved with such conventional drum-filling systems and methods is that when the inlet and outlet doors to the filling booth open, the air flow of blower 135 changes greatly. For example, when inlet door 121 opens to allow drum 101 to be indexed into booth 127, blower 135 must all of a sudden draw a much greater volume of air out of the booth, due to the changed air pressure in the booth caused by opening the door to the external environment, in order to ensure that vapors in the booth are still evacuated from the booth by the blower. Thus, blower 135 needs to be much larger and more expensive than if doors 121 and 122 were always closed, since the blower needs to be able to handle the maximum amount of air flow that can occur during the three-stage filling cycle.
Other equipment such as scrubbers or incinerators may also require more capacity to handle the maximum blower output.
Additionally, a heavier-duty blower is needed not only because the maximum volume is so high, but because of the very large change in gas flow volume to be handled.